EP1162571B1 - Verfahren und Vorrichtung zur Videobildbearbeitung zur Kompensation des Falschkontureffekts - Google Patents

Verfahren und Vorrichtung zur Videobildbearbeitung zur Kompensation des Falschkontureffekts Download PDF

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Publication number
EP1162571B1
EP1162571B1 EP20000250182 EP00250182A EP1162571B1 EP 1162571 B1 EP1162571 B1 EP 1162571B1 EP 20000250182 EP20000250182 EP 20000250182 EP 00250182 A EP00250182 A EP 00250182A EP 1162571 B1 EP1162571 B1 EP 1162571B1
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Prior art keywords
parameter
pixel
initial
difference
cell
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French (fr)
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EP1162571A1 (de
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Sébastien Weitbruch
Rainer Zwing
Carlos Correa
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Deutsche Thomson Brandt GmbH
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Deutsche Thomson Brandt GmbH
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Priority to ES00250182T priority Critical patent/ES2219263T3/es
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Priority to EP20000250182 priority patent/EP1162571B1/de
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    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/2007—Display of intermediate tones
    • G09G3/2018—Display of intermediate tones by time modulation using two or more time intervals
    • G09G3/2022—Display of intermediate tones by time modulation using two or more time intervals using sub-frames
    • G09G3/2029—Display of intermediate tones by time modulation using two or more time intervals using sub-frames the sub-frames having non-binary weights
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T5/00—Image enhancement or restoration
    • G06T5/20—Image enhancement or restoration using local operators
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/02—Improving the quality of display appearance
    • G09G2320/0261—Improving the quality of display appearance in the context of movement of objects on the screen or movement of the observer relative to the screen
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/02—Improving the quality of display appearance
    • G09G2320/0266—Reduction of sub-frame artefacts
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/10—Special adaptations of display systems for operation with variable images
    • G09G2320/106—Determination of movement vectors or equivalent parameters within the image
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/2007—Display of intermediate tones
    • G09G3/2018—Display of intermediate tones by time modulation using two or more time intervals
    • G09G3/2022—Display of intermediate tones by time modulation using two or more time intervals using sub-frames
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
    • G09G3/28—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using luminous gas-discharge panels, e.g. plasma panels
    • G09G3/2803—Display of gradations

Definitions

  • the invention relates to a method and apparatus for processing video pictures, especially for false contour effect compensation.
  • the invention is closely related to a kind of video processing for improving the picture quality of pictures which are displayed on matrix displays like plasma display panels (PDP), LCOS or display devices with digital micro mirror arrays (DMD).
  • PDP plasma display panels
  • LCOS liquid crystal display panels
  • DMD digital micro mirror arrays
  • plasma display panels are known for many years, plasma displays are encountering a growing interest from TV manufacturers. Indeed, this technology now makes it possible to achieve flat colour panels of large sizes and with limited depth without any viewing angle constraints.
  • the size of the displays may be much larger than the classical CRT picture tubes.
  • the invention deals with a specific new artefact which is called "dynamic false contour effect" as it corresponds to disturbances of gray levels and colours in the form of an apparition of coloured edges in the picuture when an observation point on the matrix screen moves.
  • the degradation is enhanced when the image has a smooth gradation like a skin. This effect leads to a serious degradation of the picture sharpness too.
  • the same problem occurs on static images when observers are shaking their heads and that leads to the conclusion that such a failure depends on the human visual perception and happens on the retina of the eye of the observer.
  • the further improvement of the false contour effect compensation is based on providing at least one correction parameter for the subjective pixel in addition to the initial parameter for the subjective pixel which is required for activating a pixel.
  • the initial parameter and the correction parameter are compared with respect to size and depending on the difference between the values it is decided whether the cell is activated with the correction parameter or with the given parameter.
  • This method has the advantage that before the correction parameter is used, it is checked whether the quality of the picture is really improved or not.
  • the general idea of the invention is to use the result of the compensation method only if it leads certainly to a higher quality of the picture.
  • This advantage is attained in an easy way by comparing the initial parameter with the correction parameter and by a decision which is made depending on the result of the comparison. So it is not necessary to change the known compensation method itself for improving the picture quality.
  • the solution based on the proposed method has the further advantage that it does not add false information in the picture, and in addition, this method is independent from the picture content and also from the sub-field organization. Also, the method is not dependent from the used addressing technique for the plasma display panel.
  • the inventive method is independent from the used compensation method and can therefore be used for different compensation methods. Therefore, the general idea of the invention can be used in all compensation methods.
  • the method according to the invention has the advantage that it is easy to implement. There is no need of a big memory since it does not need a great change of the used compensation method.
  • One important parameter which is used as a initial parameter and as a correction parameter is the time during which the pixel is illuminated in a frame period.
  • the time for illuminating the pixel decides over the quality of the video picture. A precise determination of the illuminating time is therefore necessary for a high quality. Therefore, the illumination time is used as a parameter for deciding whether the picture quality can be improved or not.
  • a good quality of the video picture is maintained if the difference is compared with a function which depends on a motion vector of the pixel.
  • the motion vector of the pixel is usually determined by a motion estimation unit.
  • the motion vector of the pixel is also an important parameter which can be used for deciding whether there should be a correction of a parameter for activating a pixel.
  • Another advantageous embodiment of the method is to compare the difference between the initial parameter and the correction parameter with a function which depends on the activating time of the pixel.
  • a function which depends on the activating time of the pixel.
  • a further improvement of the quality of the picture can be obtained if also the activating times of the pixels are considered which are located on the motion vector trajectory of the pixel. This avoids the reduction of picture sharpness in case of sharp transitions in the picture or periodical structures with sharp transitions.
  • a comparison of the difference between the initial parameter and the correction parameter of a current pixel with a function of the difference between the amplitude value of a pixel and the greatest amplitude value of the pixels, located on the motion vector assures that no loss of sharpness occurs on strong transitions (edges) in the picture.
  • Fig. 1 The artefact due to a false contour effect is shown in Fig. 1.
  • two dark lines On the arm of the woman are shown two dark lines, which for example are caused by the false contour effect. Also in the face of the woman such dark lines occur on the right side. Also luminous lines are occuring depending on video encoding and movement direction.
  • a plasma display panel utilizes a matrix array of discharge cells which could only be switched on or off. At least one cell for the colour red, blue and green is necessary for one pixel for displaying a coloured picture. For displaying a grey level picture only one single cell for one pixel is sufficient. Each cell can be controlled and activated independently from the other cells.
  • the invention is described in a simple way by using the word pixel in the meaning that the pixel consists only of a single cell. Pixel and cell are therefore used as synonyms. Also unlike a CRT or a LCD in which grey levels are expressed by analogue control of the light emission, in a PDP the gray level of a pixel is controlled by modulating the number of light pulses which the pixel sends out during a frame period.
  • This time-modulation will be integrated by the eye of an observer over a period corresponding to the eye-time response.
  • an observation point (eye-focus area) on the PDP screen moves, the eye will follow this movement. Consequently, it will no more integrate the light from the same cell over a frame period (static integration), but it will integrate information coming from different cells located on the movement trajectory. Thus it will mix all the light pulses during this movement which leads to a faulty signal information.
  • a Plasma Display Panel utilizes a matrix array of discharge cell which can only be "ON” or "OFF".
  • the PDP controls the gray level by modulating the number of light pulses per frame.
  • the eye will integrate this time modulation over a period corresponding to the human eye time-response.
  • each level will be represented by a combination of 8 bits having the following weights: 1 - 2 - 4 - 8 - 16 - 32 - 64 - 128
  • the frame period will be divided in 8 lighting periods (called sub-fields), each one corresponding to a bit.
  • each sub-field code word for a luminance representation is a 12 bit code word.
  • the light emission pattern according to the sub-field organization introduces new categories of image quality degradation corresponding to disturbances of gray levels and colours.
  • a specific term for these disturbances used in the literature is "dynamic false contour effect" since the fact that it corresponds to an apparition of coloured edges on the picture when an observation point of the PDP screen moves.
  • the observer of the picture has the impression of a strong contour appearing on an homogeneous area like displayed skin.
  • the degradation is enhanced if the image has a smooth gradation and also, when the light emission period exceeds several milliseconds. Therefore, in dark scenes the effect is not so disturbing as in scenes with average grey level (for example luminance values from 32 to 253).
  • Fig. 4 shows a darker shaded area corresponding to the luminance level 128 and a lighter shaded area corresponding to the luminance area level 127.
  • the sub-field organization shown in Fig. 2 is used for building the luminance level 128 and 127 as it is depicted on the right side of Fig. 4.
  • the three parallel lines in Fig. 4 indicate the direction in which the eye is following the movement.
  • the two outer lines indicate the borders of the area where a faulty signal will be perceived. Between them the eye will perceive a lack of luminance which leads to the appearance of a dark edge in the corresponding area which is illustrated in Fig. 5.
  • Fig. 4 there is at the bottom the eye-stimuli integration curve which shows a lower luminance between the level 128 and 127. This is shown in Fig. 5 in greater detail. On the left side of Fig. 5 there is shown a curve which illustrates the behaviour of the eye cells during observing the moving picture depicted in Fig. 4. The eye cells having a good distance from the horizontal transition will integrate light enough from the corresponding pixels.
  • Fig. 4 On the right side of Fig. 4 there is shown the picture which the observer perceives when he observes the two frames shown in Fig. 4. Between the two levels 128 and 127 there is a dark zone with a lower quantity of luminance.
  • Fig. 6 shows a situation in which an object border moves five pixels to the right side from frame N to frame N+1.
  • the light area has the level 0 and the dark area has the level 255 for the luminance.
  • the eye is following the movement of the five pixels per frame.
  • Fig. 6 is shown the eye-stimuli integration curve which shows the distribution of the luminance over the area.
  • Fig. 6 we can follow the behaviour of the eye integration during a movement.
  • the two extreme diagonal eye integration lines show the limits of the faulty perceived signal. Between them the eye will perceive a growing luminance which leads to the appearing of a shaded edge which is shown in Fig. 7. Consequently, the pure black to white transition will be lost during a movement and that leads to a reduction of the global picture sharpness impression.
  • Such a compensation applied on a moving edge will improve its sharpness on the eye retina and the same compensation applied on a moving homogeneous area will reduce the appearance of coloured edges.
  • the trajectory used for the compensation has to be converted from the geometrical definition of the vectors to a set of positions of pixels in the panel.
  • the structure of this matrix array enables only one correction applied for each pixel.
  • the eye is an analogue system and will integrate the information at a sub-pixel level. This difference will introduce a new kind of artefact which will be presented hereinafter.
  • Fig. 8 shows the principle of dynamic false contour compensation as it is described in the patent application EP 0 978 817 A1 of the applicant.
  • the example shown in Fig. 8 is the result of such a compensation method applied to the example shown in Fig. 4.
  • the contour between the first area with the luminance level of 127 and the second area with the luminance level of 128 is no more a horizontal straight line but a line with edges, whereby within one frame the second area is moving to the right side of the first area.
  • the shifting of subfield entries within one frame leads to a higher quality in the picture.
  • More details concerning the dynamic false contour compensation methods are described in the patent application EP 0 978 817 A1 and for the full disclosure of this method it is expressively referred to this document.
  • the gray curve represents the result of the eye integration on the retina. This integration leads to a perfect transition 174/176 without any artifacts. Nevertheless, such a correction, based on sub-pixel level, is not feasible; only a complete shifting of the sub-field based on a complete pixel is possible.
  • Fig. 10 At the bottom of Fig. 10 there is shown the gray curve representing the integration on the retina of an observer which is moving during the frame along the parallel axis. Because of the lack of flexibility in the sub-field shifting at low speed there is strongly visible on the gray curve an area with a too high luminance level which is shown as a white area. In said case it leads to an artefact on the retina which is much stronger than the original false contour effect. This effect is mainly visible at low speed since for such a movement, the needed sub-field shifting is very small and the lack of flexibility in a matrix array leads easily to artefacts during this kind of compensation made on bit level/bit resolution.
  • Fig. 11 the change in the amplitude domain at pixel level resulting from the correction made on sub-pixel level is depicted.
  • the amplitude domain represents the illumination energy located at each pixel on the panel and resulting from a light integration when the movement will not be followed.
  • the amplitude is directly proportional to the activation time of the pixel.
  • Fig. 11 shows one frame in which two areas are shown, whereby the first area has the luminance level 174 and the second area has the luminance level 176. There are six pixels illustrated.
  • the stripes SF1 to SF9 show the nine sub-field time periods which are available to illuminate the pixel with light pulses.
  • the diagonal lines correspond to the moving of the eye of an observer during the frame.
  • Fig. 12 shows an example for the amplitude domain of an implemented compensation. Depicted is the same situation as in Fig. 11, however, here a compensation on pixel level is applied and at the bottom of Fig. 11 the amplitude values are therefore different for the pixels of the transition.
  • This means that the compensation has added an amplitude of about 80 in energy to the second pixel, which is very high for a speed of only two pixels per frame which was used in this example.
  • the failure which appears on the retina is already detectable in the amplitude domain since it corresponds to a kind of over-compensation.
  • the over-compensation adds too much energy in the picture in comparison with the motion vector between frame N and frame N+1.
  • the amplitude domain means the level of luminance which is sent out by a cell/pixel.
  • the level of luminance is proportional to the activating time during which the cell is activated for light emission.
  • the level of false contour increases with the speed of the movement of objects between one frame and the other. This means that the level of false contour increases with the modulous of the moving vector. Therefore, in the approach according to the invention the level of compensation is advantageously limited in the amplitude domain dependent on the motion vector modulus to avoid any over-compensation effect.
  • the correction parameter is compared with the original parameter without compensation.
  • the difference between the correction parameter and the given parameter can be compared in a first advantageous embodiment of the invention with the motion vector V (x, y) at the position (x, y) at which the pixel is located, to which the original parameter and the correction parameter belong. Is the motion vector modulous greater than the difference between the correction parameter and the given parameter, then the correction parameter is used for plasma cell activation instead of the original parameter.
  • the expression parameter is used as a general term. More specifically, for the current plasma display technology, the expression "original parameter" corresponds to the original amplitude level of a colour component R,G,B of a pixel and the correction parameter corresponds to the amplitude level after applying the compensation method.
  • This basic concept has to be adapted to the different compensation methods, so that the comparison between the difference value between the original and correction parameter can be compared with a function f(t) which depends on the motion vector length.
  • a 1 , a 2 .... a n are variable and depend strongly on the coding scheme used for illuminating the pixel.
  • any other kind of function can be defined depending on the used sub-field coding and addressing methods.
  • One of the main important parameters is the illuminating time which is proportional to the amplitude of luminance of the pixel/cell. Therefore, one embodiment of the inventive method is disclosed with the following formular: The compensation result is valid when
  • a i (x, y) represents the initial amplitude of luminance of the pixel located at position (x, y)
  • a c (x, y) represents the new amplitude value which was determined by the used compensation method, represents the modulous of the motion vector at the current location
  • f loc represents a mathematical function, called "local limitation function".
  • the function can include a kind of proportionality to the initial amplitude value since the human eye is more sensitive to relative luminance (Weber Fechner Law). This means, that luminance differences are better perceived in dark areas than in light ones.
  • the test should not be limited to an amplitude value but also to a percentage value like presented in the next formula:
  • the local limitation function f loc depends on the vector amplitude ⁇ V ( x , y ) ⁇ and depends on the original amplitude A i (x,y) of the current pixel.
  • the following formula shows a simple version of the local limitation function:
  • k is a value which has to be chosen by experiments.
  • Fig. 14 presents two different similar situations which can appear in a picture.
  • the two pictures show two situations in which energy can be moved and should not be limited. In those cases a limitation of the compensation will lead to a reduction of the resolution and cause blurred edges or to the destruction of periodical structures.
  • the energy transmitted to the current part of the picture can come from the whole vector trajectory and not only from the vector origin (case of periodical structure).
  • On the left side of Fig. 14 there is shown a white and a black area, whereby an area is moving out of the black area into the white area, the corresponding motion vector is shown, too. In this case the compensation level depends on the speed and the vector origin, which lies in the black area.
  • the motion vector V which is shown describes the motion between one frame and the following frame.
  • Fig. 14 On the right side of Fig. 14 there is shown a periodical structure consisting of different black and white areas, whereby an object is moving from a white area over a black area to another white area. The movement of the area from one frame to another is shown with an arrow which illustrates the motion vector.
  • the compensation level depends on the speed of the motion which means the motion vector modulous, and the motion vector trajectory.
  • a i (x,y) represents the initial amplitude of the pixel located at the position (x, y);
  • a c (x,y) represents the new value obtained after compensation, represents the amplitude of the motion vector at the current location,
  • f traj represents a mathematical function, called trajectory limitation function.
  • the main idea of this embodiment of the invention is to take the motion vector trajectory into account for compensation control, i.e. to more reliably determine whether strong transitions are involved.
  • Fig. 15 illustrates the complete false contour algorithm principle including the amplitude limitation function in block diagram form.
  • An input 1 is connected to a frame memory 2 which itself is connected to a motion estimator 3.
  • the motion estimator 3 forwards motion vector component data V x , V y via respective data lines 7, 8 to the computing unit 4.
  • the computing unit 4 is connected to a limitation unit 5 via an output line 9.
  • the limitation unit 5 comprises an output 6 which is connected to a sub-field coding unit (not shown). After sub-field encoding the data is forwarded to the display electronics. In this electronic the addressing, sustaining and erasing periods are generated for each sub-field.
  • the activating time during which a pixel is illuminated is controlled in this unit by scanning the plasma cells and writing corresponding addressing signals in the cells. Corresponding electronic components are available from the prior art and need not be explained in detail here.
  • the limitation unit 5 forwards either the corrected sub-field code words to the display electronics or the uncorrected/original sub-field code words.
  • the input 1 is also connected to an input of the motion estimator 3, the computing unit 4 and the limitation unit 5.
  • the original parameter P i of a pixel P is sent to the frame memory 2, the motion estimator 3, the computation unit 4 and the limitation unit 5.
  • the given parameter P i is in one embodiment simply the R,G,B data for each pixel.
  • the frame memory 2 stores the R,G,B data for the time of one frame period and provides the motion estimator 3 with these values one frame later.
  • the motion estimator 3 calculates from the R,G,B values or luminance values derived therefrom of the frame N and the frame N + 1 a motion vector for each pixel P i .
  • the computing unit 4 determines out of the motion vector components V x , V y and the corresponding R,G,B values, a correction parameter P c based on amplitude level with which the pixel should be activated instead of the original parameter P i for improving the quality of the picture. Details for the compensation method on amplitude level are well known from the literature and will not be described at this place in more detail.
  • the correction parameter P c and the initial parameter P i are fed to the limitation unit 5 in parallel.
  • the limitation unit 5 decides whether the intial parameter P i or the correction parameter P c will be forwarded to the display electronics as shown.
  • the limitation is done if the original parameter and the correction parameter have a difference according to the above-mentioned formulas 1 to 5.
  • Teen of these limitation instructions can be applied singly or in any combination with each other.
  • the limitation unit 5 aims at choosing between the output of the computing unit 4 and the initial parameter P i .
  • Fig. 16 shows a preferred embodiment of the limitation unit 5.
  • the limitation unit 5 provides as an output the initial parameter P i if the difference between the initial parameter P i and the correction parameter P c is greater than a local function f loc which depends on the quantity of the motion vector V ( x , y ) and/or the initial parameter P i (x,y).
  • a trajectory function f traj which depends on the AmplitudeMAX value and the motion vector V ( x , y ) and/or the initial parameter P i (x,y).
  • the limitation unit provides at the output the initial parameter P i (x,y).
  • the correction parameter is output from limitation unit 6.
  • the corresponding formulae are shown in Fig. 16, too.
  • the false contour compensation in the computing unit 4 is performed on sub-field level as explained above and in particular in EP-A-0 978 817 A1. This means that to computing unit 4 and limitation unit 6 initial sub-field code words are fed. The computing unit 4 determines corresponding corrected sub-field code words.
  • a Sub-field encoding unit needs to be added to the block diagramme in Fig. 15 ahead of the limitation block 6.
  • the formulas applied in limitation block 6 need not be changed if the limitation block includes a transformation block in which the sub-field code words are transformed back to amplitude levels, which can be easily done according to the given sub-field organization. However, at the output of limitation unit 6 the original or corrected sub-field code words are forwarded to the display electronics.
  • the combination of the local limitation function f loc and the trajectory limitation function f traj ensures a reduction of the artefact visibility inside homogeneous areas and at strong horizontal or vertical transitions with the use of a false contour compensation.
  • the claimed invention improves the efficiency of each dynamic false contour correction based on any kind of compensation method, especially a correction based on a motion estimator since it reduces their artefacts without affecting their performances.
  • the proposed algorithm concentrates its efforts in homogeneous areas and consequently do not affect the improvement in terms of sharpness coming from the compensation and occuring on strong edges. Furthermore, periodical structures are not affected by the inventive algorithm and their sharpness still remain improved.
  • the invention does not request many modifications of existing compensation algorithms. It is only a post-processing comparison which decides whether the original parameter or the corrected parameter will be used.
  • the invention is described for the example of the activating time of the pixel as an initial parameter but the invention is not restricted to this example.
  • the invention is advantageous for any kind of parameters which should be changed by a correction parameter calculated according to a compensation method.
  • a coloured display panel there belong at least three cells to one pixel (according to the three colour components R,G,B.
  • a given parameter and a correction parameter are used for each cell. So, before using the correction parameter instead of the given parameter for activating the cell, there is a comparison according to the invention necessary for each colour component.

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Claims (14)

  1. Verfahren zur Verarbeitung von Videobildern, um falsche Kontur-Effekte zu kompensieren, wobei jedes Videobild aus Pixeln besteht und das Videobild auf einem Matrixschirm angezeigt wird, wobei ein Pixel durch wenigstens eine Zelle des Matrixschirms dargestellt wird, wobei für eine Zelle wenigstens ein Anfangs-Parameter (Pi) vorgesehen wird, der für die Steuerung der Zellenaktivierung vorgeschlagen wird, wobei für die Zelle ein Korrektur-Parameter (Pc) unter Verwendung eines Kompensationsverfahrens für eine verbesserte Bildqualität bestimmt wird, dadurch gekennzeichnet, dass der Anfangs-Parameter (Pi) und der Korrektur-Parameter (Pc) in Bezug auf Größe verglichen werden und in Abhängigkeit von einem Wert, der die Differenz zwischen beiden Parametern darstellt, entschieden wird, ob die Zellenaktivierung mit dem Korrektur-Parameter (Pc) oder mit dem gegebenen Parameter (Pi) gesteuert wird.
  2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass die Parameter eine Zeitdauer bestimmen, bei der die Zelle während einer Vollbildperiode beleuchtet wird.
  3. Verfahren nach Anspruch 2, dadurch gekennzeichnet, dass die Differenz zwischen dem Korrektur-Parameter (Pc) und dem Anfangs-Parameter (Pi) eines gegenwärtigen Pixels mit einem vorbestimmten Wert verglichen wird, das die Zellenaktivierung mit dem Korrektur-Parameter (Pc) gesteuert wird, wenn die Differenz kleiner als der vorbestimmte Wert ist, und dass die Zellenaktivierung mit dem Anfangs-Parameter (Pi) gesteuert wird, wenn die Differenz größer als der vorbestimmte Wert ist.
  4. Verfahren nach einem der vorhergehenden Ansprüche 1 bis 3, dadurch gekennzeichnet, dass der vorbestimmte Wert von einer Funktion abgeleitet wird, die von einem Bewegungsvektor eines Pixels abhängt, zu dem der Korrektur-Parameter (Pc) und der Anfangs-Parameter (Pi) gehören.
  5. Verfahren nach Anspruch 4, dadurch gekennzeichnet, dass die Funktion ferner oder alternativ von der Größe des Anfangs-Parameters (Pi) des gegenwärtigen Pixels abhängt.
  6. Verfahren nach Anspruch 4 oder 5, dadurch gekennzeichnet, dass zur Aktivierungs-Steuerung ferner ein Bildschärfe-Verbesserungs-Test durchgeführt wird, bei dem analysiert wird, ob das gegenwärtige Pixel sich in der Nähe eines starken Übergangs oder einer periodischen Struktur in dem Bild befindet.
  7. Verfahren nach Anspruch 6, dadurch gekennzeichnet, dass für den Bildschärfe-Verbesserungs-Test die Differenz zwischen dem Korrektur-Parameter (Pc) und dem Anfangs-Parameter (Pi) eines gegenwärtigen Pixels mit einem vorbestimmten Wert verglichen wird, dass die Zellenaktivierung mit dem Korrektur-Parameter (Pc) gesteuert wird, wenn die Differenz kleiner als der vorbestimmte Wert ist, und dass die Zellenaktivierung mit dem Anfangs-Parameter (Pi) gesteuert wird, wenn die Differenz größer als der vorbestimmte Wert ist.
  8. Verfahren nach Anspruch 7, dadurch gekennzeichnet, dass der vorbestimmte Wert von einer Funktion abgeleitet wird, die von der maximalen Differenz zwischen dem Anfangs-Parameter (Pi) des gegenwärtigen Pixels und dem Anfangs-Parameter der Pixel abhängt, die auf der Bewegungsvektor-Trajektorie für das gegenwärtige Pixel liegen.
  9. Verfahren nach Anspruch 8, dadurch gekennzeichnet, dass die Funktion ferner von dem Bewegungsvektor des gegenwärtigen Pixels abhängt, zu dem der Korrektur-Parameter (Pc) und der Anfangs-Parameter (Pi) gehören.
  10. Verfahren nach Anspruch 8 oder 9, dadurch gekennzeichnet, dass die Funktion ferner von der Größe des Anfangs-Parameters (Pi) des gegenwärtigen Pixels abhängt.
  11. Vorrichtung zur Verarbeitung von Videobildern, um falsche Korrektureffekte zu kompensieren, wobei die Videobilder aus Pixeln bestehen, wobei jedes Pixel durch wenigstens eine Zelle eines Anzeigeschirms dargestellt wird, wobei für die Zelle ein gegebener Parameter zum Aktivieren der Zelle vorgeschlagen wird, umfassend:
    Einen Vollbildspeicher (2) zur Speicherung des gegebenen Parameters der Zelle,
    eine Kompensationseinheit (4) für falsche Konturen zum Berechnen eines Korrektur-Parameters für die Zelle, dadurch gekennzeichnet, dass die Vorrichtung (5) eine Begrenzungseinheit (5) umfasst, dass die Begrenzungseinheit (5) den Anfangs-Parameter (Pi) mit dem Korrektur-Parameter (Pc) in der Größe vergleicht und nach einem Wert, der die Differenz zwischen dem Korrektur-Parameter und dem Anfangs-Parameter darstellt, entscheidet, ob die Zelle mit dem Anfangs-Parameter (Pi) Zelle mit dem Anfangs-Parameter (Pi) oder dem Korrektur-Parameter (Pc) aktiviert wird.
  12. Vorrichtung nach Anspruch 11, dadurch gekennzeichnet, dass diese einen Bewegungs-Abschätzer (3) aufweist, der die Bewegung eines Pixels bestimmt, wobei die Begrenzungseinheit (5) den Bewegungsvektor zur Entscheidung verwendet, ob der Anfangs- oder der Korrektur-Parameter (Pc) verwendet wird.
  13. Vorrichtung nach Anspruch 11 oder 12, dadurch gekennzeichnet, dass die Begrenzungseinheit eine Differenz zwischen dem Anfangs- und Korrektur-Parameter (Pc) berechnet und die Differenz mit einer Funktion vergleicht, die von dem Bewegungsvektor abhängt.
  14. Vorrichtung nach einem der Ansprüche 11 bis 13, dadurch gekennzeichnet, dass die Begrenzungseinheit (5) eine Differenz zwischen dem Anfangs- und dem Korrektur-Parameter (Pc) berechnet und die Differenz mit einer Funktion vergleicht, die von dem Anfangs-Parameter (Pi) abhängt.
EP20000250182 2000-06-09 2000-06-09 Verfahren und Vorrichtung zur Videobildbearbeitung zur Kompensation des Falschkontureffekts Expired - Lifetime EP1162571B1 (de)

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ES00250182T ES2219263T3 (es) 2000-06-09 2000-06-09 Procedimiento y aparato para el tratamiento de imagenes de video para la compensacion del efecto de falsos contornos.
DE2000610063 DE60010063T2 (de) 2000-06-09 2000-06-09 Verfahren und Vorrichtung zur Videobildbearbeitung zur Kompensation des Falschkontureffekts
EP20000250182 EP1162571B1 (de) 2000-06-09 2000-06-09 Verfahren und Vorrichtung zur Videobildbearbeitung zur Kompensation des Falschkontureffekts

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WO1999055078A1 (en) 1998-04-17 1999-10-28 Matsushita Electric Industrial Co., Ltd. False contour correcting apparatus and method
EP1376521A1 (de) * 2002-06-28 2004-01-02 Deutsche Thomson Brandt Videobildbearbeitung zur verbesserten Kompensation des dynamischen Falschkontureffekts
FR2880460A1 (fr) * 2005-01-06 2006-07-07 Thomson Licensing Sa Procede et dispositif d'affichage pour reduire les effets de flou
CN101777303B (zh) * 2010-03-17 2012-03-14 四川虹欧显示器件有限公司 减少等离子显示屏的动态伪轮廓的方法和装置
EP2774361B1 (de) 2011-11-01 2015-09-16 Dolby Laboratories Licensing Corporation Adaptive vorbeugung von falscher konturierung in der geschichteten bildkodierung mit erweitertem dynamikbereich
CN112070724B (zh) * 2020-08-14 2024-07-02 无锡唐古半导体有限公司 动态假轮廓的检测方法、装置、设备及计算机存储介质

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WO1998044479A1 (fr) * 1997-03-31 1998-10-08 Matsushita Electric Industrial Co., Ltd. Procede de visualisation du premier plan d'images et dispositif connexe
EP0987675A1 (de) * 1998-09-16 2000-03-22 Deutsche Thomson-Brandt Gmbh Vorrichtung und Verfahren zur Video-Bildbearbeitung, insbesondere zur Kompensation des Falschkontureneffekts

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